Method and application for preparing fluorine-containing mine water treatment agent by comprehensively utilizing coal gangue

Abstract

The present invention provides a method and application for preparing a fluorine-containing mine water treatment agent by fully utilizing coal gangue. In this method, massive coal gangue is crushed, and polyaluminum chloride coagulant is prepared through acid leaching. Additionally, a defluorination adsorbent is prepared by using rare earth to modify the acid leaching residue. The polyaluminum chloride coagulant and the defluorination adsorbent are applied to the treatment of fluorine-containing mine water. Among them, the polyaluminum chloride coagulant is used in the coagulation and precipitation treatment process of mine water, while the defluorination adsorbent is used in the defluorination treatment process. The two are connected in sequence in the treatment process, achieving efficient treatment of fluorine-containing mine water. At the same time, it also realizes the in-situ treatment and comprehensive utilization of coal gangue solid waste. The present invention has the advantages of high efficiency, economy, and high resource utilization rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of coal gangue, and particularly relates to a method for preparing a fluoride-containing mine water treatment agent by comprehensively utilizing coal gangue and its application. Background Art

[0002] The problem of excessive fluoride has become one of the main challenges for the efficient utilization of mine water in mining areas of our country. After the mine water is treated up to standard, the comprehensive utilization methods mainly include production and domestic water in coal mines, ecological irrigation in mining areas, and domestic water for residents in mining areas, etc. The corresponding standards are "Sanitary Standards for Drinking Water (GB5749-2022)" (the fluoride concentration limit is 1 mg / L) and "Environmental Quality Standards for Surface Water (GB3838-2002)" (the fluoride concentration limit for surface water of Class I, II, and III is 1 mg / L). At present, the treatment methods for fluoride-containing mine water mainly include chemical precipitation, adsorption, ion exchange, membrane separation, etc. Among them, the adsorption method has been widely used due to its simple operation, high efficiency, and low cost.

[0003] Coal gangue is a kind of rock that coexists with coal seams and is a solid waste generated during coal mining and coal washing processes. The main component is silicate, which contains about 40-60% of SiO 2 and 15-50% of Al 2 O 3 , and it is an excellent siliceous-aluminous mineral raw material. However, due to its low activity, the utilization efficiency of coal gangue is not high, resulting in a large amount of coal gangue being piled up in mining areas, causing serious waste of resources, environmental pollution, and economic losses. Therefore, processing coal gangue to produce high-value-added products will have certain economic and environmental benefits.

[0004] Using coal gangue to prepare aluminum salt coagulants by acid method for water treatment has the advantages of fast floc formation, good precipitation performance, less consumption of alkalinity in water, and strong adaptability to changes in water temperature, pH value, turbidity, and organic matter content. In the prior art, when using coal gangue to prepare aluminum salt coagulants, a large amount of silicon-based solid waste will be generated. These silicon-based solid wastes are not effectively treated, which will not only cause waste of resources but also cause secondary pollution to the environment. Summary of the Invention

[0005] In order to overcome the above technical problems, the purpose of the present invention is to provide a method for preparing a fluoride-containing mine water treatment agent by comprehensively utilizing coal gangue and its application. This method prepares polyaluminum chloride coagulants by acid leaching, and uses rare earth-modified acid leaching residues to prepare defluorination adsorbents, which are applied to the treatment of fluoride-containing mine water to achieve efficient treatment of fluoride-containing mine water, and at the same time realize the on-site treatment and comprehensive utilization of coal gangue solid waste.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a fluorine-containing mine water treatment agent by fully utilizing coal gangue, comprising the following steps;

[0008] Step (1): Screening the lumpy coal gangue into coal gangue powder after ball milling by a ball mill;

[0009] Step (2): Placing the coal gangue powder obtained in step (1) in a muffle furnace for high-temperature roasting and activation, and obtaining activated coal gangue after the furnace is naturally cooled;

[0010] Step (3): Dispersing the activated coal gangue obtained in step (2) in a hydrochloric acid solution, centrifuging the solid-liquid mixture after acid leaching reaction, and the supernatant obtained is aluminum chloride solution, and the precipitate is coal gangue acid leaching residue;

[0011] Step (4): Adding sodium aluminate to the aluminum chloride solution obtained in step (3), adjusting the pH value of the reaction system to reach 3-5, carrying out a polymerization reaction and aging to obtain a polyaluminum chloride coagulant;

[0012] Step (5): Washing the coal gangue acid leaching residue obtained in step (3) three times with deionized water and drying, adding lanthanum nitrate and cerium sulfate solution, and stirring at 25-45 °C for 1-1.5 h to fully impregnate to obtain coal gangue acid leaching residue loaded with cerium & lanthanum;

[0013] Step (6): After drying the coal gangue acid leaching residue loaded with cerium & lanthanum obtained in step (5), placing it in a muffle furnace for high-temperature roasting to obtain a defluorination adsorbent;

[0014] Step (7): The polyaluminum chloride coagulant removes the suspended solids in the fluorine-containing mine water, and the defluorination adsorbent removes the fluoride ions in the fluorine-containing mine water. The polyaluminum chloride coagulant and the defluorination adsorbent together form a fluorine-containing mine water treatment agent.

[0015] Further, the particle size of the coal gangue powder after ball milling in step (1) is 150 mesh.

[0016] Controlling the particle size of the coal gangue powder aims to increase the reaction surface area, thereby improving the efficiency of subsequent reactions, especially the solubility during the acid leaching process.

[0017] Further, in step (2), the high-temperature roasting and activation, the roasting temperature is 700-850 °C, and the roasting time is 1.5-2.5 h.

[0018] The purpose of high-temperature roasting is to activate the coal gangue and improve its chemical reactivity. The temperature range is to adapt to the compositional differences of different coal gangues and avoid over-roasting resulting in reduced activity.

[0019] Further, the solid-liquid ratio of the activated coal gangue to the hydrochloric acid solution in step (3) is 1:3 to 1:5; the mass fraction of the hydrochloric acid solution is 20%, the acid leaching temperature is 80 to 95 °C, and the acid leaching time is 1.5 to 2.5 h.

[0020] Controlling the solid-liquid ratio is to ensure that the acid solution and the coal gangue can fully contact and react during the acid leaching process, thereby improving the leaching efficiency. Appropriate temperature and time can optimize the rate and efficiency of the acid leaching reaction. At a higher temperature, the reaction rate is faster, but too high a temperature may lead to unnecessary side reactions, so it needs to be controlled within a reasonable range.

[0021] Further, the polymerization temperature in step (4) is 70 to 90 °C, the polymerization time is 1 to 2 h, the aging temperature is 20 to 30 °C, and the aging time is 20 to 30 h.

[0022] The setting of the temperature and time of the polymerization reaction is to ensure the full formation of polyaluminum chloride and avoid adverse effects on the polymerization process due to too high or too low temperature. The aging reaction helps to improve the stability and performance of the product. By controlling the temperature and time, ensure that the reaction is completed and the desired product is obtained.

[0023] Further, the solid-liquid ratio of the acid leaching residue of coal gangue to the lanthanum nitrate and cerium sulfate solution in step (5) is 1:1 to 1:3; the molar ratio of lanthanum nitrate to cerium sulfate is 1:1; the loading ratio of lanthanum and cerium is 15 to 35%.

[0024] The setting of the solid-liquid ratio and the molar ratio is to ensure that the acid leaching residue of coal gangue can fully react with the lanthanum nitrate and cerium sulfate solution. The molar ratio of 1:1 can optimize the reaction ratio of rare earth elements and avoid the excess of a certain element affecting the performance of the product. The range of the loading ratio helps to enhance the adsorption effect.

[0025] Further, the roasting temperature in step (6) is 500 to 650 °C, and the roasting time is 0.3 to 1 h.

[0026] Through high-temperature roasting, the structure and chemical stability of the material are enhanced. Controlling the range of temperature and time helps to fully fix lanthanum and cerium on the material surface and optimize the pore structure of the material.

[0027] Another object of the present invention also provides the application of the fluorine-containing mine water treatment agent composed of polyaluminum chloride coagulant and defluorination adsorbent prepared by the above method in the treatment of fluorine-containing mine water.

[0028] The polyaluminum chloride coagulant and defluorination adsorbent are prepared by the described preparation method. Among them, the polyaluminum chloride coagulant is used in the coagulation and sedimentation treatment process of mine water, while the defluorination adsorbent is used in the defluorination treatment process. The two are in a sequential connection relationship in the process of treating fluorine-containing mine water, jointly realizing the efficient treatment of fluorine-containing mine water.

[0029] Advantages of the present invention:

[0030] (1) The massive coal gangue is ground by a ball mill and then screened into coal gangue powder. By grinding the massive coal gangue into fine powder through ball milling, the contact area of the coal gangue is significantly increased, making it easier to contact with media such as heat and acid in subsequent roasting activation and acid leaching reactions, thereby improving the reaction efficiency.

[0031] (2) The coal gangue powder is placed in a muffle furnace for high-temperature roasting activation, and the activated coal gangue is obtained after the furnace naturally cools. High-temperature roasting causes thermal decomposition and phase transformation of inorganic components (such as aluminosilicates) in the coal gangue, forming a porous structure and improving the chemical activity of the coal gangue. At the same time, high-temperature roasting can remove organic impurities in the coal gangue, reducing its interference with subsequent reactions.

[0032] (3) The activated coal gangue is dispersed in a hydrochloric acid solution with a mass fraction of 20%. After the acid leaching reaction, the solid-liquid mixture is centrifuged, and the supernatant obtained is aluminum chloride solution, and the precipitate is coal gangue acid leaching residue. Hydrochloric acid reacts with aluminum oxide in the activated coal gangue to form aluminum chloride solution, providing raw materials for the subsequent preparation of polyaluminum chloride. Through centrifugal separation, soluble aluminum chloride is separated from insoluble coal gangue acid leaching residue, realizing the efficient utilization of resources.

[0033] (4) Sodium aluminate is added to the aluminum chloride solution until the pH value of the reaction system reaches 3 - 5, and polymerization reaction and aging are carried out to obtain the polyaluminum chloride coagulant. Controlling the pH value within the range of 3 - 5 ensures that the polyaluminum chloride has a high charge neutralization ability and adsorption bridging effect, and is suitable for the treatment of complex water bodies such as mine water.

[0034] (5) The coal gangue acid leaching residue is washed three times with deionized water and then dried. Lanthanum nitrate and cerium sulfate solutions are added, and it is stirred at 25°C for 1.5 h to make it fully impregnated to obtain coal gangue acid leaching residue loaded with cerium & lanthanum. By washing the coal gangue acid leaching residue with deionized water, residual hydrochloric acid is removed, avoiding interference with the subsequent loading process. Through the impregnation method, lanthanum nitrate and cerium sulfate are loaded onto the coal gangue acid leaching residue. Utilizing the high-efficiency adsorption performance of rare earth elements (cerium and lanthanum), the defluorination ability of the material is improved. The introduction of cerium and lanthanum forms more active sites on the surface of the coal gangue acid leaching residue, significantly increasing its adsorption capacity and selectivity for fluoride ions.

[0035] (6) The cerium- and lanthanum-loaded acid leaching residue of coal gangue is placed in a muffle furnace for high-temperature roasting after drying to obtain a defluorination adsorbent. High-temperature roasting enables the rare earth elements to form stable chemical bonds with the surface of the coal gangue acid leaching residue, preventing the rare earth elements from falling off during use and further optimizing the pore structure and surface properties of the material. As Figure 2 shown, the surface of the defluorination adsorbent presents a layered structure and has layered crystals. Abundant pore structures are formed between these layered crystals, endowing the surface of the defluorination adsorbent with more available adsorption sites, increasing its specific surface area and adsorption performance, and facilitating the removal of fluoride ions from aqueous solutions.

[0036] The present invention realizes the efficient treatment of fluorine-containing mine water, and at the same time realizes the in-situ treatment and comprehensive utilization of coal gangue solid waste, having the advantages of economy, high efficiency, and high resource utilization rate. Brief Description of the Drawings

[0037] Figure 1 is the process flow diagram for preparing a coagulant and an adsorbent using coal gangue.

[0038] Figure 2 is the scanning electron microscope photograph of the defluorination adsorbent.

[0039] Figure 3 is the adsorption capacity of the adsorbent for fluoride ions in Application Example 3. Detailed Description of the Embodiments

[0040] The present invention will be further described in detail below with reference to the accompanying drawings.

[0041] The coal gangue in the examples was purchased from Wuhai Energy Co., Ltd., China National Energy Group, and lanthanum nitrate and cerium sulfate were purchased from Macklin.

[0042] Coal gangue contains abundant elements such as silicon, aluminum, and iron and is a solid waste;

[0043] Lanthanum nitrate has a strong electrostatic attraction ability with fluoride ions and can form stable La-F bonds;

[0044] Cerium sulfate can enhance the adsorption ability for fluoride ions through valence changes;

[0045] Preparation Example 1

[0046] As Figure 1 shown, a method for preparing a fluorine-containing mine water treatment agent by fully utilizing coal gangue includes the following steps;

[0047] (1) The massive coal gangue is ball-milled by a ball mill and then screened to obtain 150-mesh coal gangue powder;

[0048] (2) Place the coal gangue powder obtained in step (1) in a muffle furnace and calcine it at a high temperature of 750 °C for 2 h. After the furnace cools naturally, activated coal gangue powder is obtained;

[0049] (3) Disperse the activated coal gangue powder obtained in step (2) in a hydrochloric acid solution with a mass fraction of 20%. After acid leaching at 90 °C for 2.5 h, centrifuge the solid-liquid mixture. The supernatant obtained is aluminum chloride solution, and the residual solid substance is coal gangue acid leaching residue; among them, the solid-liquid ratio of activated coal gangue powder to hydrochloric acid is 1:5;

[0050] (4) Add sodium aluminate to the aluminum chloride solution obtained in step (3), adjust the pH value of the reaction system to 3, then stir at 80 °C for 1.5 h for polymerization reaction. After the polymerization reaction is completed, ripen at 20 °C for 24 h to obtain a polyaluminum chloride coagulant;

[0051] (5) Wash the coal gangue acid leaching residue obtained in step (3) three times with deionized water and then dry it. Add lanthanum nitrate and cerium sulfate solution, and stir at 25 °C for 1.5 h to fully impregnate it to obtain coal gangue acid leaching residue loaded with cerium & lanthanum, where the molar ratio of lanthanum nitrate to cerium sulfate is 1:1, and the loading ratio of lanthanum and cerium is 15%;

[0052] (6) After drying the coal gangue acid leaching residue loaded with cerium & lanthanum obtained in step (5), place it in a muffle furnace and calcine it at a high temperature of 500 °C for 0.5 h to obtain a defluorination adsorbent.

[0053] Preparation Example 2

[0054] (1) Grind the massive coal gangue with a ball mill and then sieve it to obtain 150-mesh coal gangue powder;

[0055] (2) Place the coal gangue powder obtained in step (1) in a muffle furnace and calcine it at a high temperature of 800 °C for 2.5 h. After the furnace cools naturally, activated coal gangue powder is obtained;

[0056] (3) Disperse the activated coal gangue powder obtained in step (2) in a hydrochloric acid solution with a mass fraction of 20%. After acid leaching at 85 °C for 2.5 h, centrifuge the solid-liquid mixture. The supernatant obtained is aluminum chloride solution, and the residual solid substance is coal gangue acid leaching residue; among them, the solid-liquid ratio of activated coal gangue powder to hydrochloric acid is 1:4;

[0057] (4) Add sodium aluminate to the aluminum chloride solution obtained in step (3), adjust the pH value of the reaction system to 3.5, then stir at 85 °C for 1.5 h for polymerization reaction. After the polymerization reaction is completed, ripen at 25 °C for 24 h to obtain a polyaluminum chloride coagulant;

[0058] (5) Wash the acid-leached gangue residue obtained in step (3) three times with deionized water and then dry it. Add lanthanum nitrate and cerium sulfate solutions, and stir at 25 °C for 1.5 h to fully impregnate it to obtain cerium- and lanthanum-loaded acid-leached gangue residue, where the molar ratio of lanthanum nitrate to cerium sulfate is 1:1, and the loading ratio of lanthanum and cerium is 20%;

[0059] (6) After drying the cerium- and lanthanum-loaded acid-leached gangue residue obtained in step (5), place it in a muffle furnace and calcine it at a high temperature of 550 °C for 0.5 h to obtain a defluorination adsorbent.

[0060] Preparation Example 3

[0061] (1) Grind the massive gangue with a ball mill and then screen it to obtain 150-mesh gangue powder;

[0062] (2) Place the gangue powder obtained in step (1) in a muffle furnace and calcine it at a high temperature of 850 °C for 2.5 h for activation. After the furnace cools naturally, obtain activated gangue powder;

[0063] (3) Disperse the activated gangue powder obtained in step (2) in a 20% hydrochloric acid solution by mass fraction, and carry out acid leaching at 80 °C for 2.5 h. Then centrifuge the solid-liquid mixture to obtain the supernatant as aluminum chloride solution and the residual solid matter as acid-leached gangue residue; among them, the solid-liquid ratio of the activated gangue powder to hydrochloric acid is 1:3;

[0064] (4) Add sodium aluminate to the aluminum chloride solution obtained in step (3), adjust the pH value of the reaction system to 4, and then stir at 90 °C for 1.5 h for polymerization reaction. After the polymerization reaction is completed, ripen at 30 °C for 24 h to obtain a polyaluminum chloride coagulant;

[0065] (5) Wash the acid-leached gangue residue obtained in step (3) three times with deionized water and then dry it. Add lanthanum nitrate and cerium sulfate solutions, and stir at 25 °C for 1.5 h to fully impregnate it to obtain cerium- and lanthanum-loaded acid-leached gangue residue, where the molar ratio of lanthanum nitrate to cerium sulfate is 1:1, and the loading ratio of lanthanum and cerium is 25%;

[0066] (6) After drying the cerium- and lanthanum-loaded acid-leached gangue residue obtained in step (5), place it in a muffle furnace and calcine it at a high temperature of 600 °C for 0.5 h to obtain a defluorination adsorbent.

[0067] Application Example 1

[0068] (1) Prepare a 1000 mg / L sodium fluoride solution with sodium fluoride, and then dilute it to 50 mg / L. Take 100 ml of the 50 mg / L sodium fluoride solution into a polyethylene bottle, add a certain amount of kaolin, and stir well to make the turbidity of the solution reach 30 NTU; obtain fluoride-ion-containing simulated mine water with a concentration of 50 - 150 mg / L;

[0069] (2) Weigh 0.3 g of the polyaluminum chloride coagulant and 0.1 g of the defluorination adsorbent prepared in Preparation Example 1 respectively;

[0070] (3) Adjust the pH values of the sodium fluoride solution in step (1) to 1, 3, 5, 7, 9, and 11. Then, place 0.3 g of the polyaluminum chloride coagulant into a polyethylene bottle and carry out coagulation precipitation at room temperature. The coagulation time is 30 min. The turbidity removal rates measured are 23.6%, 35.4%, 51.8%, 75.7%, 89.5%, and 92.6% respectively;

[0071] (4) Filter the solution after coagulation precipitation in step (3), add 0.1 g of the defluorination adsorbent thereto, carry out adsorption treatment at room temperature, centrifuge after oscillating in a water bath thermostatic oscillator for 9 h, and measure the concentration of fluoride ions. The adsorption amounts are 23.12 mg / g, 38.59 mg / g, 47.322 mg / g, 36.55 mg / g, 18.54 mg / g, and 1.39 mg / g respectively.

[0072] Application Example 2

[0073] (1) Prepare a 1000 mg / L sodium fluoride solution with sodium fluoride, then dilute it to 50 mg / L. Take 100 ml of the 50 mg / L sodium fluoride solution into a polyethylene bottle, add a certain amount of kaolin, and stir well to make the turbidity of the solution reach 30 NTU; obtain fluoride ion-containing simulated mine water with a concentration of 50 - 150 mg / L;

[0074] (2) Weigh 0.3 g of the polyaluminum chloride coagulant and 0.1 g of the defluorination adsorbent prepared in Preparation Example 1 respectively;

[0075] (3) Under the condition of adjusting the pH value of the sodium fluoride solution in step (1) to 5, then place 0.3 g of the polyaluminum chloride coagulant into a polyethylene bottle and carry out coagulation precipitation at room temperature. The coagulation times are 10, 20, 30, 40, and 50 min respectively. The turbidity removal rates measured are 59.1%, 68.3%, 77.5%, 86.7%, and 90.1% respectively;

[0076] (4) Add 0.1 g of the defluorination adsorbent to the polyethylene bottle in step (3), carry out adsorption treatment at room temperature, centrifuge after oscillating in a water bath thermostatic oscillator for 1, 2, 4, 6, and 9 h respectively, and measure the concentration of fluoride ions. The adsorption amounts are 44.75 mg / g, 44.39 mg / g, 45.06 mg / g, 46.59 mg / g, and 47.43 mg / g respectively.

[0077] Application Example 3

[0078] (1)Prepare a sodium fluoride solution with a concentration of 1000 mg / L using sodium fluoride, and then dilute it to 50 mg / L. Take 100 ml of the sodium fluoride solution with a concentration of 50 mg / L into a polyethylene bottle, add a certain amount of kaolin, and stir well to make the turbidity of the solution reach 30 NTU; obtain fluoride ion-simulated mine water with a concentration of 50 - 150 mg / L;

[0079] (2)Weigh 0.3 g of the polyaluminum chloride coagulant and 0.1 g of the defluorination adsorbent prepared in Preparation Example 1 respectively;

[0080] (3)Under the condition of adjusting the pH value of the sodium fluoride solution in step (1) to 5, then place 0.3 g of the polyaluminum chloride coagulant into the bottle, and carry out coagulation precipitation at 25 °C, 35 °C, and 45 °C respectively. The coagulation time is 30 min, and the turbidity removal rates are measured to be 89.8%, 91.6%, and 93.2% respectively;

[0081] (4)Add 0.1 g of the defluorination adsorbent to the polyethylene bottle in step (3), carry out adsorption treatment at 25 °C, 35 °C, and 45 °C respectively, centrifuge after oscillating in a water bath constant temperature oscillator for 9 h, measure the concentration of fluoride ions, and the adsorption amounts are 45.16 mg / L, 42.42 mg / L, and 41.12 mg / L respectively. As Figure 3 shown, with the increase of the pH value, the adsorption amount of fluoride ions shows a trend of first increasing and then decreasing. When the pH value is 5, the adsorption performance of the defluorination adsorbent is the best.

[0082] The above embodiments have described the present invention in detail, but they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components, characterized in that: The steps include: Step (1): grinding the coal gangue block by a ball mill and then sieving it into coal gangue powder; Step (2): placing the gangue powder obtained in step (1) in a muffle furnace for high-temperature calcination and activation, and then naturally cooling the furnace to obtain activated gangue; Step (3): dispersing the activated coal gangue obtained in step (2) in a hydrochloric acid solution, centrifuging the solid-liquid mixture after the acid leaching reaction, and obtaining a supernatant as an aluminum chloride solution and a precipitate as coal gangue acid leaching residue; Step (4): adding sodium aluminate to the aluminum chloride solution obtained in step (3), adjusting the pH value of the reaction system to 3 to 5, performing a polymerization reaction and aging to obtain a polyaluminum chloride coagulant; Step (5): washing the coal gangue acid leaching residue obtained in step (3) with deionized water three times and then drying, adding lanthanum nitrate and cerium sulfate solution, stirring at 25 to 45° C. for 1 to 1.5 hours to fully impregnate the coal gangue acid leaching residue to obtain cerium and lanthanum loaded; Step (6): after drying, the cerium and lanthanum loaded on the coal gangue acid leaching slag obtained in step (5) is placed in a muffle furnace for high-temperature roasting to obtain a defluorination adsorbent; Step (7): The polyaluminium chloride coagulant and the defluorination adsorbent together constitute a fluorine-containing mine water treatment agent, wherein the polyaluminium chloride coagulant is used to remove suspended matter in the fluorine-containing mine water, and the defluorination adsorbent is used to remove fluoride ions in the fluorine-containing mine water.

2. The method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components according to claim 1, characterized in that: The particle size of the coal gangue powder after ball milling in step (1) is 150 mesh.

3. The method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components according to claim 1, characterized in that: The high temperature calcination activation in step (2) has a calcination temperature of 700 to 850° C. and a calcination time of 1.5 to 2.5 hours.

4. The method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components according to claim 1, characterized in that: The solid-liquid ratio of the activated coal gangue to the hydrochloric acid solution in step (3) is 1:3 to 1:5; the mass fraction of the hydrochloric acid solution is 20%, the acid leaching temperature is 80 to 95° C., and the acid leaching time is 1.5 to 2.5 hours.

5. The method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components according to claim 1, characterized in that: In step (4), the polymerization temperature is 70-90°C, the polymerization time is 1-2h, the aging temperature is 20-30°C, and the aging time is 20-30h.

6. The method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components according to claim 1, characterized in that: In step (5), the solid-liquid ratio of the coal gangue acid leaching residue to the lanthanum nitrate and cerium sulfate solution is 1:1 to 1:3; the molar ratio of lanthanum nitrate to cerium sulfate is 1:1; and the loading ratio of lanthanum to cerium is 15 to 35%.

7. The method for preparing a fluorine-containing mine water treatment agent using coal gangue as all components according to claim 1, characterized in that: The calcination temperature in step (6) is 500-650° C., and the calcination time is 0.3-1 h.

8. Use of a fluorine-containing mine water treatment agent composed of a polyaluminium chloride coagulant and a defluorination adsorbent prepared according to the method of any one of claims 1 to 7 in the treatment of fluorine-containing mine water.

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